If you’re anything like me, I need my cup of coffee in the morning, so I have tons of used coffee grounds leftover. I always wondered whether I could make good use of them in the garden. Can you plant seeds in coffee grounds?
You should generally avoid using coffee grounds as a medium for planting seeds because of the high content of acid and caffeine. Many swear by its properties, but the science shows the opposite: Used coffee grounds will stunt plants’ growth, even the most acid-loving ones.
Although you should not use coffee grounds as a potting soil medium, there are other uses for it in your garden. Let’s see how!
Why can’t I use coffee grounds as a potting medium?
There are quite a few well-established reasons why you should not use coffee grounds as a soil medium. First and foremost, as mentioned above, the caffeine content of coffee grounds. Secondly, the acidity levels of coffee grounds I know what you are thinking: don’t some plants prosper in acidity rich soil? The answer is yes, but there are no plants that thrive with caffeine. Even after you have used your grounds, they still contain at least 47mg of caffeine, which is more than a cup of black tea.
The caffeine in the grounds stunts, and sometimes even kills, plants or seedlings outright. It happens because caffeine forces plants to release the calcium content of their cellular walls. The absence of calcium in the plant cell walls, in turn, stunts the plant from growing and the seeds from germinating. Caffeine also binds up all the nitrogen in the soil and contributes to the degradation of the plant’s growth.
According to this study, the more coffee grounds you use in your soil mix, the less likely your seeds will germinate.
Because Coffee grounds also tend to be compacted and compressed when used as a soil medium, it sometimes forms a rock-like substance. This substance drains water poorly, which results in plants and seedlings withering and dying due to root rot or overwatering.
There are many alternatives to using coffee grounds as a potting or germinating medium. You can use Coconut Coir or Coconut fibers, Peat Moss, Perlite, or Vermiculite for germinating purposes. All of these have different qualities, so be sure to ask your local garden center which is best for your needs.
Instead of mixing coffee grounds into your potting soil, mix Perlite, sterilized soil and, Peat Moss in equal quantities for a winning recipe. This mixture will provide excellent drainage, aeration of the soil, and enough solidity to anchor the plants’ roots.
What can I use coffee grounds for in my garden?
Despite the high acidic and caffeine levels in coffee grounds, there are still uses for it in your garden. Chief amongst them is compost, which enriches the nutrient levels of your soil.
Making your very own compost is easy, and unless you drink a coffee shop’s worth of coffee a month, it’s impossible to overdo it.
All you need is:
- A bin or container made from wood or plastic, depending on your preference
- Hessian or Burlap to line the inside of your container
- 25% Coffee grounds, 25% Garden waste such as leaves or grass, 25% Straw or Twigs, and 25% Manure and soil
As mentioned before, line your container with Burlap or Hessian and then start filling your compost bin with the said materials. Make sure to mix thoroughly to allow the compost to aerate. If the mixture seems dry, you can add some water. Cover or close your compost bin, leave it for approximately three months, turn it over and leave it for another three months. This might seem unnecessary, but the materials must aerate and decompose properly. At the end of 6 months, your compost should be brown, crumbly to touch, and have a sickly sweet smell to it. This indicates that your coffee ground compost is ready to use.
Alternatively, you can use coffee grounds in small amounts mixed directly in your soil. However, bear in mind that using too much will stunt your plants’ growth or even kill them. The golden rule here is to remember that less is more. Sprinkle your coffee grounds onto the surface of your soil and mix well. Do not leave the coffee grounds on the surface of your soil, as dried coffee grounds can prevent water from penetrating your soil.
What About Fungi?
You could also use your coffee grounds to grow mushrooms. Wait, I thought you said plants could not grow in coffee grounds? Yes, but mushrooms are fungi, and although they are notoriously tricky to grow, it is not impossible. Follow the tips below, and you will have your own little container of mushrooms in no time!
- Grab an old Styrofoam cooler, large freezer bag, or bucket
- Combine 5.5 pounds of your coffee grounds with a pound of mushroom spore and sawdust mixture. You should be able to find the spores at your local gardening center.
- Fill your container until two-thirds full with your coffee grounds and mushroom spore mix. If you are using a closed container, cut four small air openings above the grounds on the container’s sides. If you are using an open container like a bag or lidless plastic bin, you can cover it with cellophane and poke small air holes.
- Use a spray bottle to lightly water the coffee grounds daily to ensure they remain damp. Once the shrooms have started to bud in two to four weeks, you can move them to an area with fresher air.
- Once the mushrooms’ caps turn upward, and the mushrooms themselves have plumped up, it is harvest time.
Where else can I use my coffee grounds?
Outside of your garden, coffee grounds have multiple uses. Below are some ideas you can use to utilize your old coffee grounds best:
Have you accidentally burned food in your microwave or left something too long in your fridge? No worries, just put an uncovered jar filled with coffee grounds in your appliance. Within a week, the odor should be gone.
For those who are more hands-on in the kitchen, you can use coffee grounds to deodorize your hands after chopping onions or garlic. Just rub a small hand full of the used coffee grounds into and on top of your hands. This has the added benefit of leaving your hands not smelling of garlic or onion and exfoliating your hands, leaving your skin soft and smooth.
- Cleaning your pots and pans
Why would you use coffee grounds to clean your dirty pots and pans? Easy, because of the texture and composition, coffee grounds will not damage your pots and pans like other abrasive cleaning utensils. Rub the coffee grounds onto your already dirty cookware, and with a little elbow grease and water, your pots and pans should be spic and span in no time.
- Cleaning your stainless grill
While every man has different barbequing methods, we can all agree that stainless steel grills should not be cleaned with wire brushes. A green and easy alternative is coffee grounds. Just sprinkle the coffee grounds over your grill and use a sponge with some hot water to scour it off gently. The coffee grounds will serve as a soft abrasive while bonding to all the gunk stuck on the grill. Afterward, rinse with hot water, and you should have a shiny grill.
- Natural Mosquitoe Repelent
I don’t think I have ever met someone who likes being bitten by mosquitoes, and if you live near any large body of freshwater, you know how it feels to be eaten alive at night. To relieve yourself and your loved ones from the insect vampires, take a metal or glass ashtray and fill it halfway with coffee grounds. Pour a few drops of lighter fluid on it and light it with a barbeque lighter or match. Once the grounds start smoking, use a damp kitchen towel to smother the coffee grounds. The grounds should keep on burning without producing too much smoke, leaving you and your family to enjoy a night outdoors without the pesty company of mosquitoes.
Another pest controlling tip is to use coffee grounds as a deterrent for ants. If you can find their nest or the opening to the anthills, you should be able to dissuade the ant from entering your home by sprinkling coffee grounds on the hills or at the thresholds of your home.
We have learned that coffee grounds have their place in your garden and around your home. And when combined with a little creativity, grounds can be utilized in many other different ways. Just not for germinating or planting your seeds in.